Category: Map

January 20, 2016

Since its rise in popularity, the well-known online encyclopedia Wikipedia has been struggling with manipulation or, in the worst-case, vandalism attempts. Similarly, the OpenStreetMap (OSM) project suffered several times over the past few years of cases where incorrect map data edits were made. These erroneous edits can stem at times from (new) contributors or illegal data imports (or automated edits) which have not been discussed in advance with the community or the Data Working Group (DWG) and corrupted existing project data. The current OSM wiki page gives a great overview about general guidelines and e.g. types of vandalism. Another page in the wiki also mentions a prototype of a rule based system for the automatic detection of vandalism in OSM, which I developed in 2012. However, the system has never actually been implemented. Today, the contributors of OSM can use a variety of different tools to inspect an area or particular map changes. A few of them are listed below (complete list can be found here):

June 5, 2013

Last year we wrote a journal paper in which we analyzed the OpenStreetMap (OSM) dataset of the United States which was published on May 28th, 2013 in the Transactions in GIS Journal. You can download a free pre-print version here. This paper has been published just on time to add to the discussion at the upcoming State of the Map United States conference which will take place in San Francisco and includes some presentations about data imports to OSM. Unfortunately, Dennis and I cannot attend the conference this year, so we decided to write a blog post with some additional and up-to-date numbers.

January 6, 2013

The wait is over! As I mentioned in December, I have been working on an interactive online map, which shows you all volunteers of the OpenStreetMap world on a map. The first three layers contain the activity center of a contributor, her or his first created and latest modified node. The algorithm to determine the activity area of an OSM volunteer has been described in my publication here. I should mention that I used all changeset centers instead of all created nodes of a contributor. This way the computations don’t take as long and the process can be repeated every week based on the weekly OSM changeset dump.

November 16, 2012

Two years ago, we created some maps which showed you the number of users per country for a timeframe of one month. Maybe some of you remember that the highest concentration of active contributors in relation to the countries’ population could be found in Europe. We thought it was about time to make some new maps to see if things have changed. The following map shows you the number of active contributors per day per country.

Similar to our results two years ago, the above map only gives some general information about the total number of users per country and does not consider the population for each country. Therefore we created a second map which shows you the relation between active users and the population in each country per day.

Now, in a second step I created a worldwide grid, with an edge length of 15km, to show in more detail where the GPS points are located. The rendering of the tiles has been accomplished with the great TileMill software. Usually you would see some GPS noise in the grid cells above the equator. Thus, to eliminate this noise and to create a better overview, grid cells with less than 5 GPS points are made transparent. The following image shows an overview of Europe and the corresponding OSM GPS density. Of course you can also see some quite interesting and funny airplane, ferry or cruise routes.